It is known that the measurements made by an angle-of-attack probe can be used by various systems with which said aircraft is equipped, and especially by said aircraft's electrical flight control.
Generally, an aircraft, for example a civil transport airplane, is fitted with a plurality of angle-of-attack probes. In this case, the measurements from one of said angle-of-attack probes are selected, for example with the aid of a polling means, with a view to their processing by user systems with which the aircraft is equipped.
By way of example, when the aircraft is fitted with three angle-of-attack probes simultaneously monitored by said polling means, the latter selects from among the three measurements made by the probes, the one exhibiting the median value.
Moreover, in this case, one of said angle-of-attack probes is declared to be faulty when the value which it delivers deviates by more than a predefined threshold factor from said median value.
This mode of detecting faults or inconsistency of the measurements from angle-of-attack probes is not entirely satisfactory, especially as regards its reliability. Indeed, if in the aforesaid case, two of the three angle-of-attack probes become faulty simultaneously, for example on account of the aircraft colliding with a flock of birds, they may transmit, on account of their unbalance, the same information. In this case, the aforesaid usual mode of detecting faults uses the information from these two faulty angle-of-attack probes as accurate and reliable and declares the third angle-of-attack probe, which continues to operate normally, to be faulty.
The object of the present invention is to overcome these drawbacks. It relates to a reliable process which is simple and rapid to implement and which makes it possible to verify the consistency of the measurements made by at least one angle-of-attack probe mounted on an aircraft.
To this end, according to the invention, said process is noteworthy in that:
at least one measurement is made by means of said angle-of-attack probe; PA1 a first coefficient of lift of the aircraft is computed from said measurement and from data relating to the aircraft; PA1 a second coefficient of lift of the aircraft is computed from information available about said aircraft; PA1 the difference is computed between said first and second coefficients of lift of the aircraft; and PA1 from this is deduced: PA1 the load factor nz is measured by an accelerometer of the aircraft; and/or PA1 the dynamic pressure Pd is measured by an anemometer of the aircraft. PA1 a first computing means for computing said first coefficient of lift; PA1 a second computing means for computing said second coefficient of lift; and PA1 a central unit for verifying the consistency of the measurements of the angle-of-attack probe, on the basis of the computations made by said first and second computing means.
if the difference thus computed is less than a predefined value, that the measurement made by the angle-of-attack probe is consistent; and PA2 otherwise, that said measurement is inconsistent.
Thus, by virtue of the invention, an effective and reliable check of the consistency of the measurements of an angle-of-attack probe is obtained, which check is in particular independent of the measurements made by the other angle-of-attack probes of the aircraft and enables the aforesaid drawbacks to be overcome.
Advantageously, the data relating to the aircraft, which are used in computing the first coefficient of lift, represent aerodynamic data of the aircraft and data representative of its flight configuration.
Preferably, the position of the slats, of the flaps and of the airbrakes of the aircraft, together with the latter's Mach number are used as data representative of the flight configuration.
Furthermore, advantageously, said second coefficient of lift Cz2 is computed from the relation: EQU Cz2=(nz.m.g)/(0.5.Pd.S)
in which:
nz is the load factor of the aircraft;
m is the mass of the aircraft;
g is the acceleration due to gravity;
Pd is the dynamic pressure; and
S is a reference surface area of the aircraft.
Moreover, advantageously:
Furthermore, in a first variant, the effective mass of the aircraft, which is measured, is used as mass m, whereas, in a second variant, the maximum mass of the aircraft is used as mass m.
The present invention applies more particularly to an aircraft fitted with a plurality of angle-of-attack probes and with a means of selection for selecting measurements from measurements made by said angle-of-attack probes. In this case, said means of selection can in particular be a polling means, such as mentioned above, or a computing element which for example averages the various measurements made by said angle-of-attack probes.
According to the invention, only the consistency of said selected measurements is thus verified.
The present invention also relates to a device for implementing the aforesaid process.
According to the invention, said device is noteworthy in that it comprises: